1. Preheat oven to 225°C/440° F.
2. Combine the garlic and oil in a large bowl,
warming it until the garlic is fragrant, about 1
3. Transfer 5 tablespoons of the oil (leaving the
garlic in the bowl) to the baking dish, coating it
4. Add the potatoes to the bowl with the garlic
mixture and toss to coat. Wrap tightly in plastic
wrap and microwave on high power until the
potatoes are translucent around the edges, 3 to 6
minutes, shaking the bowl to redistribute the
potatoes halfway through cooking.
5. Combine the cornstarch, salt, pepper, garlic
powder, and cayenne in a small bowl. Sprinkle over
the hot potatoes and toss well to coat.
6. Arrange the potatoes in a single layer on the
prepared baking sheet and bake, turning once,
until deep golden brown and crisp, 30 to 40
7. Serve with ketchup, mayo or sour cream.